1. Field of the Invention.
The present invention relates to the field of crude oil production and, more specifically, to a system and method for collecting hydrocarbon fluid that is escaping through a breach in a well pipe of a hydrocarbon producing well. The terms “hydrocarbon producing well,” “hydrocarbon well,” “oil well,” and “well” are used synonymously in this application.
2. Background of the Invention.
A typical hydrocarbon production well includes a production pipe nested within a casing pipe that provides support to the borehole of the well. While the production pipe communicates hydrocarbons to the surface, surrounding casing pipes primarily serve to reinforce the main borehole. Casing pipe, or casing, is an essential component of the well completion. For example, the casing prevents the formation wall from caving into the wellbore. Moreover, the casing provides a way for a well operator to control formation fluids and pressure as the well is drilled. A casing pipe must operate in a difficult environment and is subjected to a variety of forces and corrosive chemicals.
Generally, the production pipe and casing pipes are made of steel, which is susceptible to oxidation and corrosion over time that may cause the oil well to leak hydrocarbon fluids or gases through the casing pipes and into the surrounding earth. These leaked hydrocarbons may eventually surface at ground level and, as they move through the earth, cause a harmful environmental impact to surface and underground water and soil, as well as wildlife, during migration to the surface. Furthermore, any leaking oil translates to lost revenue and reduced efficiency of the well, especially when is a large volume of producer. Not surprisingly, the larger the breach in a casing pipe, the more revenue is lost.
Traditional methods for addressing this problem required the well operator to stop production and withdraw the leaking casing or production pipe from the well to seal the breach. Not only is this undesirable because of the lost revenue due to a production stop, but this can potentially create an economic disincentive for even repairing the smaller leaks; in other words, it may be more profitable to continue production despite the presence of a small leak in the casing rather that cease producing long enough to repair the leak. Such economic disincentive may make economic sense, but would not make environmental sense, as the surrounding earth, nearby water sources, and the wildlife ultimately pay a heavy price.
A review of the prior art in the field reveals other attempts at maintaining the integrity of well casing. Some inventions merely test the physical integrity of the production tubing or casing without repairing the breach. For example, U.S. Pat. No. 5,267,469 provides a method for testing the physical integrity of casing by applying a test pressure to the inner annular space of the wellbore and monitoring the test pressure for a pressure drop. By measuring the pressure in a sealed-off portion of the well annulus—the area between the production tubing and casing—and applying a known test pressure, the pressure can be monitored. Any drop in the test pressure indicates a breach in either the production tubing or the casing. The patent makes no provision, however, for repairing any such breach.
U.S. Pat. No. 3,194,310 discloses both locating and repairing the leak. A breakable capsule containing a sealing compound is disposed into the well to the position of the breach. After sealing the tubing both above and below the breach, the capsule is broken to allow the sealant to flow around the tool and be contained between the seals. Importantly, however, the production tubing must be removed from the well—and thus production substantially disrupted—to use the tool and method taught to seal a breach in the casing pipe.
Similarly, U.S. Pat. No. 3,364,993 also teaches a method of well casing repair in which the method of repairing a leak in a well pipe comprises placing an expansible patch around the breach, inflating the patch by injecting fluid into the patch to expand and set the patch against the breach. As with U.S. Pat. No. 3,194,310, though, this method disrupts the production piping within the well.